Tough hydrogel coating and method of manufacture

Abstract

Hydrogel-substrate laminate structures and tough biocompatible hydrogel coatings for various equipment such as medical devices and underwater equipment, in which robust interfaces are formed between the hydrogel coatings and the substrate/equipment surface(s). The hydrogel coatings provide a highly-hydrated, ultra-low friction structure that does not rupture or delaminate under stress. The hydrogel coatings may further incorporate a variety of therapeutic agents and/or sensing mechanisms to provide for environmental sensing and therapeutic agent release.

What is claimed is: 
     
         1 . A hydrogel-substrate laminate comprising:
 a layer of substrate having a top surface and a bottom surface, the substrate selected from elastomers, plastics, glass, ceramics and metals;   at least one hydrogel coating layer disposed on one or more of the top surface and the bottom surface of the substrate; and   one or more therapeutic agent disposed within the at least one hydrogel coating layer, and/or one or more sensing material disposed within the at least one hydrogel coating layer.   
     
     
         2 . The hydrogel-substrate laminate according to  claim 1 , wherein a first hydrogel coating layer is disposed on the top surface of the substrate layer, and a second hydrogel coating layer is disposed on the bottom surface of the substrate layer. 
     
     
         3 . The hydrogel-substrate laminate according to  claim 2 , wherein the layer of substrate is impermeable to small molecules, a first therapeutic agent is disposed within the first hydrogel coating layer, and a second therapeutic agent different than or the same as the first therapeutic agent is disposed within the second hydrogel coating layer. 
     
     
         4 . The hydrogel-substrate laminate according to  claim 2 , wherein the layer of substrate is impermeable to small molecules, a first sensing material is disposed within the first hydrogel coating layer, and a second sensing material different than or the same as the first sensing material is disposed within the second hydrogel coating layer. 
     
     
         5 . The hydrogel-substrate laminate according to  claim 2 , wherein the layer of substrate is impermeable to small molecules, at least one therapeutic agent is disposed within the first hydrogel coating layer, and at least one sensing material is disposed within the second hydrogel coating layer. 
     
     
         6 . The hydrogel-substrate laminate according to  claim 1 , wherein at least on therapeutic agent and at least one sensing material are disposed within the at least one hydrogel coating layer,
 wherein the at least one therapeutic agent and the at least one sensing material are in communication, and   wherein release of the at least one therapeutic agent from the at least one hydrogel coating layer is controlled by one or more environmental conditions sensed by the at least one sensing material.   
     
     
         7 . The hydrogel-substrate laminate according to  claim 6 , wherein the at least one therapeutic agent is disposed within a first hydrogel coating layer, and the at least one sensing material is disposed within a second hydrogel coating layer, wherein the first and second hydrogel coating layers are separated from each other by the layer of substrate. 
     
     
         8 . The hydrogel-substrate laminate according to  claim 1 , wherein the thickness of the hydrogel coating layer is predetermined to provide a hydrogel-substrate laminate having mechanical properties ranging from mechanical properties of the pure substrate to mechanical properties of the pure hydrogel. 
     
     
         9 . The hydrogel-substrate laminate according to  claim 1 , wherein the at least one hydrogel coating layer comprises:
 a physically crosslinked dissipative polymer network selected from PVA, collagen, gelatin, agar, agarose, dextran, alginate, hyaluronan and chitosan; and   a covalently crosslinked stretchy polymer network selected from polyacrylamide (PAAm), polyethylene glycol (PEG), polyethylene glycol derivatives, polyvinyl alcohol, poly-N,N-dimethylacrylamide (DMMA), polyacrylamide derivatives, and polyzwitterionic monomers.   
     
     
         10 . The hydrogel-substrate laminate according to  claim 8 , wherein the substrate is an elastomer material, and the stretchy polymer network in the hydrogel coating layer is covalently grafted to elastomer chains of the elastomer material. 
     
     
         11 . A hydrogel coated medical device comprising:
 a medical device having an outer surface;   at least one hydrogel coating layer disposed on at least a portion of the outer surface of the medical device; and   one or more therapeutic agent disposed within the at least one hydrogel coating layer to provide therapeutic agent release into an environment surrounding the at least one hydrogel coating layer, and/or one or more sensing material disposed within the at least one hydrogel coating layer to provide sensing of one or more environmental conditions surrounding the at least one hydrogel coating layer.   
     
     
         12 . The hydrogel coated medical device of  claim 10 , wherein the hydrogel coated medical device has a coefficient of friction less than the medical device without the hydrogel coating layer. 
     
     
         13 . The hydrogel coated medical device of  claim 10 , wherein at least on therapeutic agent and at least one sensing material are disposed within the at least one hydrogel coating layer,
 wherein the at least one therapeutic agent and the at least one sensing material are in communication, and   wherein release of the at least one therapeutic agent from the at least one hydrogel coating layer is controlled by one or more environmental conditions sensed by the at least one sensing material.   
     
     
         14 . The hydrogel coated medical device of  claim 10 , wherein a plurality of different therapeutic agents are disposed within the at least one hydrogel coating layer so as to be independently released from the at least one hydrogel coating layer. 
     
     
         15 . A method for fabricating a hydrogel-substrate laminate comprising:
 activating at least one surface of a pristine substrate material, the substrate material selected from elastomers, plastics, glass, ceramics and metals;   coating at least one surface of the activated substrate material with a layer of hydrogel precursor solution;   curing the hydrogel precursor solution to thereby form a tough, double network hydrogel coating layer of controllable thickness firmly grafted on the at least one surface of the activated substrate material.   
     
     
         16 . The method of  claim 15 , wherein the hydrogel precursor solution contains one or more therapeutic agent and/or one or more sensing material. 
     
     
         17 . The method of  claim 15 , further comprising, prior to curing the hydrogel precursor solution, predetermining desired mechanical properties of the hydrogel-substrate laminate ranging from mechanical properties of the pure substrate to mechanical properties of the pure hydrogel, and based on the desired mechanical properties, determining a corresponding thickness of the hydrogel coating layer, and placing of at least one spacer on the layer of hydrogel precursor solution to control a thickness of the hydrogel coating layer. 
     
     
         18 . The method of  claim 15 , wherein activating at least one surface of a pristine substrate material comprises surface functionalization of the substrate surface. 
     
     
         19 . The method of  claim 15 , wherein the hydrogel coating layer is formed by grafting hydrogel polymer chains onto the substrate surface by generation of free radicals at the substrate-hydrogel interface.